1. Field of the Invention
This invention relates to a disc cartridge comprised of a disc-shaped recording medium, above all, an optical disc or a magneto-optical disc, as accommodated in a cartridge and, more particularly, to such a disc cartridge which is provided with a shutter for opening or closing a recording/reproducing aperture formed in the cartridge. The present invention also relates to a shutter opening/closing device for opening or closing the shutter of the disc cartridge.
2. Description of the Prior Art
As shown in FIGS. 1 and 2, there has hitherto been proposed a disc cartridge 103 which is comprised of a disc 101, such as an optical disc or a magneto-optical disc, as a disc-shaped recording medium adapted for writing and/or reading information signals, and a cartridge housing 102 for rotatably accommodating the disc 101.
With such disc cartridge 103, the cartridge housing 102 is provided with a recording/reproducing aperture 104 by means of which the disc 101 may be partially exposed to the outside across its inner and outer peripheries. The disc cartridge 103 is also provided with a shutter member 105 movable with resect to the cartridge housing 102. The recording/reproducing aperture 104 is opened or closed when the shutter member 105 is moved with respect to the cartridge housing 102.
When the disc 101 is not in use, the recording/reproducing aperture 104 is closed by the shutter member 105 to prevent foreign matter or the user's hand or finger from being intruded into the inside of the cartridge housing 102.
When the disc 101 is to be in use, the cartridge housing 102 with the disc 101 accommodated therein is attached to a cartridge holder 106 of a recording/reproducing apparatus, not shown. The cartridge holder 106 includes a holder 107 which is substantially box-shaped to permit the cartridge housing 102 to be inserted therein and which is fitted with a shutter-opening lever 108 for opening the shutter member 105. The holder 107 is also fitted with a detection lever 110 for detecting the insertion of the cartridge housing 102 in an inappropriate direction.
The shutter-opening lever 108 has its proximal end fulcrumed at the middle of a major surface of the holder 107 by means of a pivot 108a. A shutter opening pin 108 is set upright on the distal end of the shutter-opening lever 108. This shutter-opening pin 108b depends into the interior of the holder 107 by way of a slit 109 formed in a major surface of the holder 107 along a locus of movement of the shutter-opening pin 108b which is centered about the pivot 108a. This shutter opening lever 108 is positioned at an initial position by being biased, by biasing means, not shown, in a direction of shifting the shutter opening pin 108b towards the forward side of the disc holder 107, as shown by an arrow in FIG. 10.
The detection lever 110 has its proximal end rotatably supported at a lateral side on the major surface of the holder 107 by means of a pivot 110a. A detection pin 110b is set on the distal end of the detection lever 110. The detection pin 110b depends into the inside of the holder 107 by way of a notch 111 formed on the lateral side of the holder 107. This detection lever 110 is positioned at an initial position by being biased, by biasing means, not shown, in a direction of shifting the detection pin 110b towards the inner side of the disc holder 107, as shown by an arrow f in FIG. 10.
When the disc cartridge 103 is introduced into the holder 107 of the cartridge holder 106, in a direction shown by an arrow a in FIG. 2, with the side of the shutter member 105 as the inserting end, the shutter opening pin 108b is inserted into a shutter opening recess 102b formed at one lateral side of the shutter member 105 of the cartridge 102. If the disc cartridge 103 is further introduced towards the interior of the holder 107, as shown by an arrow a in FIG. 2, the shutter-opening pin 108b is thrust by a shutter opening pin guide surface 102c extending continuously to the bottom surface of the shutter opening recess 102b. The shutter-opening pin 108b rotates the shutter-opening lever 108 in a direction shown by an arrow b in FIG. 2. The shutter member 105 is then thrust by the shutter-opening pin 108b and thereby shifted with respect to the cartridge housing 102 in a direction of opening the recording/reproducing aperture 104, as shown by an arrow C in FIG. 2.
One lateral side of the forward end of the cartridge housing 102, to which the shutter member 105 is attached, is formed with a chamfered edge 102a for the inappropriate inserting detection of the disc cartridge. This chamfered edge 102a is formed by obliquely removing the corner of the cartridge housing 102. When the disc cartridge 103 is introduced into the holder 107 in the normal direction, the detection pin 110b abuts on the chamfered edge 102a. This causes the detection lever 110 to be rotated outwardly of the holder 107, as shown by an arrow d in FIG. 2, to permit further intrusion of the cartridge housing 102 into the inside of the holder 107. Should it be tried to introduce the disc cartridge 103 into the holder 107 in the inappropriate direction, the detection lever 110 is not rotated, because the detection pin 110b abuts on the lateral side of the cartridge housing 102. Thus the detection lever 110 inhibits further intrusion of the cartridge housing 102 into the inside of the holder 107.
When the disc cartridge 103 is introduced further into the inside of the holder 107, the shutter-opening pin 108b is intruded into a recess 102d for shutter-opening pin 108b formed in continuation to the shutter opening pin guide 102c. Thus the position is reached in which the disc cartridge 103 is mounted in position within the holder 107. At this time, the recording/reproducing aperture 104 is opened, so that the disc 101 is exposed across its inner and outer peripheries towards the outside of the cartridge housing 102.
In the above described recording and/or reproducing apparatus, a pickup unit for writing and/or reading information signals, not shown, is adapted for facing the portion of the disc 101 which is exposed to outside by means of the recording and/or reproducing apparatus. A chucked section 101a, provided at the center of the disc 101, is held by a chuck unit, not shown, of the recording and/or reproducing apparatus.
In this state, the disc 101 is rotated by means of the chuck unit so that the information signals are written and/or read by means of the pickup device.
With the above described disc cartridge, a variety of discs having different structures and properties are used as the disc-shaped recording media. The properties of a disc-shaped recording medium include the volume of the information signals that may be recorded per unit area on the medium, that is the recording density, the quantity of the energy required for writing and/or reading the information signals, or the like.
Thus it is necessary to use such a recording and/or reproducing apparatus which, depending on the type of the disc-shaped recording medium, is capable of writing and/or reading the information signals in accordance with the properties and/or format of the disc-shaped recording medium. If the disc-shaped recording medium is inserted into a recording and/or reproducing apparatus which is not suited thereto, not only may the information signals not be recorded or reproduced, but also the disc-shaped recording medium may be destroyed.
Thus it has been customary with the disc cartridge that the cartridge of a different shape is used depending on the type of the disc-shaped recording medium to prevent the situation in which the cartridge housing accommodating a disc-shaped recording medium not suited to the recording and/or reproducing apparatus is inserted into the recording and/or reproducing apparatus. For example, it has been undertaken to use the cartridges of different thicknesses as a function of the types of the disc-shaped recording media accommodated therein, or to change the position and/or shape of the chamfered edge provided in the cartridge as a function of the disc-shaped recording media for preventing inappropriate insertion of the disc cartridge.
However, if it should be attempted to discriminate the types of the recording media by changing the cartridge shape, it is difficult to cope with a number of types of the disc-shaped recording media. That is, the cartridge has a moderate range of thickness, depending on the thickness of the recording medium, and can not be simply reduced or increased in thickness. Should the cartridge thickness not be appropriate for the thickness of the disc-shaped recording medium, it becomes difficult to write and/or read information signals on or from the disc/shaped recording medium, to achieve smooth rotation of the disc-shaped recording medium in the cartridge, to accommodate the disc in the cartridge housing, or to store the disc cartridge. Besides, there are only two places in which to provide the chamfered edge for detection of mistaken insertion, that is, one or the other edge on the forward side of the cartridge by which the cartridge may be inserted into the holder.
On the other hand, should the cartridge shape be changed to suit the types of the disc-shaped recording media, it becomes necessary to design the recording and/or reproducing apparatus with a different shape to suit to the different cartridge, thus complicating the design and/or manufacture of the recording and/or reproducing apparatus.